Role of the standard 'liver function tests' in current clinical practice.

A prerequisite of current therapy in liver disease is precise diagnosis. The rapid increase in the number of tests available--immunological, virological, histological and radiological--testifies to this, and reflects the inadequacy of the 'standard' liver function tests (LFTs). The LFTs are, however, in contrast to these more sophisticated tests, observer independent and despite their lack of specificity, several characteristic patterns of abnormality can be recognised which direct the physician to the most appropriate definitive investigation. The cheapness and non-invasive nature of the LFTs makes them particularly appropriate for monitoring the course of liver diseases once the diagnosis has been established and this, together with screening for hepatotoxicity of newly developed drugs, is now their main role. A second generation of liver function tests based on the capacity of the liver to eliminate various test compounds may come closer to offering a true estimate of liver function. More accurate methods of measuring the various bilirubin fractions, particularly bilirubin conjugates may also become available in the near future and provide more sensitive tests of liver dysfunction.